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Why do we measure plant BRIX levels

SoilScopes offers BRIX testing services

What does BRIX level mean?

BRIX measures the sugar, vitamins, minerals, Amino acid proteins and other solid content found in the sap of a plant. The BRIX level of the plant is expressed on a scale and measured through light refraction of the plant's sap. The concentration of the sugars, amino acids and other solid contents in the sap reflect light when tested which is a reading on the BRIX scale. Represented as a unit of °Bx degrees the reading most refractometers measure is the scale between 1 - 25. BRIX shows us how densely packed the sap of a plant is with important biological compounds which aid the plant in the defence against pests and diseases. A plant with a high BRIX reading will be more resistant to a range of stress factors due to the extra resources available stored in the sap. Opposed to plants with a low BRIX reading which is susceptible to a great number of pests, diseases and stress factors. A high BRIX reading will indicate the plant nutrition is optimal and the plant will have high turgid pressure. Turgid pressure is the force of the plant sap pressing the cell membrane against the cell wall which gives plants crisp and firm leaves. If turgid pressure is low plants will appear wilted and unable to hold their form. So BRIX levels are pretty important!

What are the benefits of testing your BRIX levels?

We test BRIX levels of plants to determine if the available nutrition is being processed adequately. If the BRIX levels are out of range it is a good indicator that the plant does have access to the nutrients it requires. It also indicates that pests are beginning to notice your plants as easier targets because the plant's defences are lowered. The lens through which many insect pests see the world is very different to our own. Their senses detect weaker plants very accurately which allows them to pick out the unhealthiest plants with the lowest BRIX level. Plants with a high BRIX appear as less desirable to pests to the point where at certain levels where the plant is unpalatable to pests. This is why we aim high when it comes to the BRIX level.

Another useful reason you may want to test BRIX levels is to determine the efficacy of your nutrient applications. Whether you are using fertilisers, organic inputs or focused on soil health you want to know how effectively the nutrient is being uptaken by your plants. By doing a baseline BRIX test prior to an application of plant nutrients you can determine how well it was processed by the plant through another BRIX test a week later. By keeping track of your crop's BRIX levels you can be sure that plant nutrition is within optimal range and pest pressure will remain low.

Testing BRIX levels of the fruit or vegetable are also useful to indicate overall flavour, storage potential and ripeness. The nutritional content of high BRIX fruit and veg is higher and provides more sustenance for whoever eats it. Plants with high BRIX translate to produce that stores longer on the shelf because of the increased turgid pressure. This means overall happier consumers of the food as it lasts longer and tastes better.

High BRIX levels means that plants are using the nutrition effectively

How can I raise the BRIX level in my plants?

Having the correct levels of available nutrients means that plants have all they would need to build the organic compounds such as amino acids or carbohydrates which registers on the BRIX test. With any cultivation method hitting the right levels of available nutrients can be challenging but that is what we need to do to achieve high BRIX. The best place to start is always Soil Health.

Plants grown in soil rich with microbial life will have a much high nutrient availability for plants to uptake. The microorganisms are constantly cycling nutrients into the most bioavailable form right at the roots of the plant. The symbiotic relations between plants and microbes is a blog post all by itself but the key point is this; When the soil has abundant, active and aerobic microorganisms the plants which grow in it have the perfect forms of nutrients available to them at all times. There is no guesswork in fertiliser applications and plants grow healthier with a higher BRIX level.

Applications of biomcomplete compost, worm castings or another high-value microbial product can really help you with this process. Improving the conditions of the soil will give your plant what it needs to raise its BRIX levels. It takes time to improve the soil to the point where it can supply the plant with everything it needs without the need for external fertilisers. Putting soil health first means putting microorganisms first.

How do you test the BRIX level in plants?

A Refractometer is used to determine the BRIX level of your plants. This is a service that SoilScopes offers to farmers, gardeners or growers who want to assess their plant's health. Start by extracting the sap of the plant and placing it on the lens of a refractometer. You then look through the eyepiece which needs to be pointed at a light source. The screen will display a reading of the BRIX levels which should then be recorded in a log. Plants should be tested a number of times over a season, particularly at critical growth phases.

What is a good BRIX level for my crops?

Many different pests can target your crops but we almost never see all the possible pests affecting your plants at the same time. The reason being is that pests are picky, they have a preference for a certain BRIX range when attacking that specific crop. It also relates to their senses which are attuned to plants within their preferred BRIX range.

BRIX LEVEL : 1 - 4

Very low range and the plant is unlikely able to protect itself from any pest or disease that comes in contact with it.


Plants in this range are most susceptible to aphids. They will not be able to prevent the pest from taking over without pesticide application


Other sucking insects like mealybug or spider mites will have a preference for plants in this range.


​This is a higher range and the plant is producing compounds which protect it from a number of pests. However, chewing insects like caterpillars and worms are still able to bypass the plant's defences.

BRIX LEVEL 12 - 14

A very good range for BRIX with only the most tenacious grasshoppers being able to palate these BRIX levels. Very little need for pest control is needed.


Extremely resilient to any pest due to the high production of secondary metabolites which prevent the pests from feeding. Plant nutrition is performing very well.

BRIX levels affect the pest that affect the plants

What reduces BRIX levels in plants?

  • Applications of many high Nitrogen fertilisers and other synthetic pest control solutions will reduce the soil's microorganism populations. This needs to be avoided if you wish to increase your plant's BRIX value.

  • An excess of Nitrogen in nitrate form also swells the leaves with excess water. This will decreases the BRIX levels as more water in the leaves means a decrease in the concentration of sugars and amino acids.

  • Timing is important. Low temperatures can result in an inaccurate BRIX reading. Along with afternoons which result in higher-than-normal readings. It is recommended that readings be taken at a consistent time at some point in the morning as the plants receive their first light of the day. Having your tests done at consistent times means you can reduce the impact of the above two factors.

SoilScopes offers BRIX testing

If you are interested in getting your crop's BRIX levels tested click HERE to contact us for our offerings on BRIX testing. We will handle the onsite BRIX testing which is done extensively across your cultivation area to get an accurate representation of the health of the crop. You will receive a full BRIX report with the findings along with analysis and recommendations for your crops needs. Keep a track of your crop's health by using our BRIX testing service!


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